Партнёры:
Хостинг:
head - display first few lines of files
/usr/bin/head [-number | -n number] [filename]...
head [-qv] [-n lines] [-c chars] [-s skip][filename]...
The head utility copies the first number of lines of each filename to the standard output. If no filename is given, head copies lines from the standard input. The default value of number is 10 lines.
When more than one file is specified, the start of each file looks like:
==> filename <==
Thus, a common way to display a set of short files, identifying each one, is:
example% head -9999 filename1 filename2 ...
The head built-in in ksh93 is associated with the /bin and /usr/bin paths. It is invoked when head is executed without a pathname prefix and the pathname search finds a /bin/head or /usr/bin/head executable.
head copies one or more input files to standard output, stopping at a designated point for each file or to the end of the file whichever comes first. Copying ends at the point indicated by the options. By default, a header of the form ==> filename <== is output before all but the first file but this can be changed with the -q and -v options. If no file is given, or if the file is -, head copies from standard input starting at the current location.
The option argument for -c and -s can optionally be followed by one of the following characters to specify a different unit other than a single byte:
b
k
m
For backwards compatibility, -number is equivalent to -n number.
The following options are supported by /usr/bin/head:
-n number
-number
If no options are specified, head acts as if -n 10 had been specified.
The following options are supported by the head built-in command in ksh93:
-n
--lines=lines
-c
--bytes=chars
-q
--quiet|silent
-s
--skip=skip
-v
--verbose
The following operand is supported:
filename
See largefile(5) for the description of the behavior of head when encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).
Example 1 Writing the First Ten Lines of All Files
The following example writes the first ten lines of all files, except those with a leading period, in the directory:
example% head *
See environ(5) for descriptions of the following environment variables that affect the execution of head: LANG, LC_ALL, LC_CTYPE, LC_MESSAGES, and NLSPATH.
The following exit values are returned:
0
>0
See attributes(5) for descriptions of the following attributes:
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The ksh93 built-in binding to /bin and /usr/bin is Volatile. The built-in interfaces are Uncommitted.
cat(1), ksh93(1), more(1), pg(1), tail(1), attributes(5), environ(5), largefile(5), standards(5)
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